scholarly journals Adsorption Performance of Physically Activated Biochars for Postcombustion CO2 Capture from Dry and Humid Flue Gas

2020 ◽  
Vol 10 (1) ◽  
pp. 376 ◽  
Author(s):  
Joan J. Manyà ◽  
David García-Morcate ◽  
Belén González
Keyword(s):  
Wheat Straw ◽  
Co2 Capture ◽  
Co2 Adsorption ◽  
Packed Bed ◽  
Dry Conditions ◽  
Stable Performance ◽  
High Concentrations ◽  
Hierarchical Pore ◽  
Cyclic Adsorption ◽  
Adsorption Desorption

In the present study, the performance of four biomass-derived physically activated biochars for dynamic CO2 capture was assessed. Biochars were first produced from vine shoots and wheat straw pellets through slow pyrolysis (at pressures of 0.1 and 0.5 MPa) and then activated with CO2 (at 0.1 MPa and 800 °C) up to different degrees of burn-off. Cyclic adsorption-desorption measurements were conducted under both dry and humid conditions using a packed-bed of adsorbent at relatively short residence times of the gas phase (12–13 s). The adsorbent prepared from the vine shoots-derived biochar obtained by atmospheric pyrolysis, which showed the most hierarchical pore size distribution, exhibited a good and stable performance under dry conditions and at an adsorption temperature of 50 °C, due to the enhanced CO2 adsorption and desorption rates. However, the presence of relatively high concentrations of water vapor in the feeding gas clearly interfered with the CO2 adsorption mechanism, leading to significantly shorter breakthrough times. In this case, the highest percentages of a used bed were achieved by one of the other activated biochars tested, which was prepared from the wheat straw-derived biochar obtained by pressurized pyrolysis.

scholarly journals Carbon Dioxide Adsorption on Carbon Nanofibers with Different Porous Structures

2021 ◽  
Vol 11 (16) ◽  
pp. 7724 ◽  
Author(s):  
Yu-Chun Chiang ◽  
Chih-Cheng Huang ◽  
Wei-Ting Chin
Keyword(s):  
Carbon Nanofibers ◽  
Co2 Capture ◽  
Co2 Adsorption ◽  
Breakthrough Curves ◽  
Porous Structures ◽  
Carbon Dioxide Adsorption ◽  
Cyclic Tests ◽  
Surface Areas ◽  
Co2 Adsorption Capacity ◽  
Hierarchical Pore

Electrospinning techniques have become an efficient way to produce continuous and porous carbon nanofibers. In view of CO2 capture as one of the important works for alleviating global warming, this study intended to synthesize polyacrylonitrile (PAN)-based activated carbon nanofibers (ACNFs) using electrospinning processes for CO2 capture. Different structures of PAN-based ACNFs were prepared, including solid, hollow, and porous nanofibers, where poly(methyl methacrylate) (PMMA) was selected as the sacrificing core or pore generator. The results showed that the PMMA could be removed successfully at a carbonization temperature of 900 °C, forming the hollow or porous ACNFs. The diameters of the ACNFs ranged from 500 to 900 nm, and the shell thickness of the hollow ACNFs was approximately 70–110 nm. The solid ACNFs and hollow ACNFs were microporous materials, while the porous ACNFs were characterized by hierarchical pore structures. The hollow ACNFs and porous ACNFs possessed higher specific surface areas than that of the solid ACNFs, while the solid ACNFs exhibited the highest microporosity (94%). The CO2 adsorption capacity on the ACNFs was highly dependent on the ratio of V<0.7 nm to Vt, the ratio of Vmi to Vt, and the N-containing functional groups. The CO2 adsorption breakthrough curves could be curve-fitted well with the Yoon and Nelson model. Furthermore, the 10 cyclic tests demonstrated that the ACNFs are promising adsorbents.

Biochar From Cocoa Shell Pyrolysis: Potential Sorbent for CO2 Capture

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Hamed Abedini Najafabadi ◽  
Nesrin Ozalp ◽  
Richard A. Davis
Keyword(s):  
Activated Carbon ◽  
Co2 Capture ◽  
Co2 Adsorption ◽  
Lignin Content ◽  
Co2 Uptake ◽  
Rate Limiting Step ◽  
Pseudo Second Order ◽  
Cocoa Shell ◽  
The Stability ◽  
Adsorption Desorption

Abstract Biochar produced from slow pyrolysis of cocoa shells was studied as a sorbent for CO2 capture. Three cocoa shell samples obtained from Papua New Guinea, Peru, and Colombia were studied. Thermogravimetric analysis showed that the first three stages of degradation were quite similar for different cocoa shell sources. However, the fourth stage was different, which could be due to the different lignin content in the cocoa shell sources. Chemical analysis showed that the cocoa shell biochar had a lower content of carbon and oxygen, and a higher content of magnesium, potassium, and calcium compared with the cocoa shell. CO2 uptake performance of the cocoa shell biochar was examined and compared with a commercial activated carbon using a thermogravimeter at atmospheric pressure and ambient temperature. The final CO2 uptake after 30 min was slightly higher for cocoa shell biochar. However, activated carbon had a faster adsorption response, and it approached equilibrium faster than the cocoa shell biochar. This could be due to differences in particle size, pore structure, and surface area of the activated carbon which allows the CO2 to be adsorbed easily in its porous structure. A pseudo-second-order model of kinetics fits the CO2 adsorption behavior of cocoa shell biochar and activated carbon indicating that the rate-limiting step is chemical adsorption. Furthermore, the stability of the cocoa shell sorbent was confirmed over four adsorption/desorption cycles. By considering the simplicity of the production process and efficiency of CO2 adsorption, cocoa shell biochar can be considered a good option for CO2 capture.

scholarly journals Treatment of Dynamic Mixture of n-Hexane, Benzene, and Methanol and Fungi Community Characterization in an Integrated Scheme of Cyclic Adsorption/Desorption Beds and Trickle Bed Air Biofilter

2015 ◽  
Vol 8 ◽  
pp. ASWR.S23688 ◽  
Author(s):  
Abderrahman Zehraoui ◽  
George A. Sorial
Keyword(s):  
Control Unit ◽  
Average Concentration ◽  
The Other ◽  
Loading Rates ◽  
Volatile Organic ◽  
Stable Performance ◽  
Trickle Bed Air Biofilter ◽  
Trickle Bed ◽  
Cyclic Adsorption ◽  
Adsorption Desorption

This study investigates the effect of volatile organic compound (VOC) feed fluctuations on trickle bed air biofilters (TBABs) and the ability of a two-bed adsorption/desorption unit in dampening fluctuations. A mixture of n-hexane, benzene, and methanol with concentration ratios of 1:3:6.6 was fed to two parallel TBABs. To simulate feed fluctuations, four different square waves were applied. The total VOC loading rates (LRs) varied from 28.4 to 107.3 g/m3 h. The average concentration of VOCs applied to both TBABs was within allowable limits as determined in an earlier study. One TBAB was preceded by a two-bed cyclic adsorption/desorption unit (integrated unit), while the other TBAB (control unit) was directly subjected to the high and low peaks. n-Hexane elimination in the integrated unit was steady, and stable performance was obtained (75%-89%) based on the LRs, whereas the control unit showed erratic performance. The other two VOCs were mostly removed.

scholarly journals Influence of the Presence of Different Alkali Cations and the Amount of Fe(CN)6 Vacancies on CO2 Adsorption on Copper Hexacyanoferrates

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3371 ◽  
Author(s):  
Svensson ◽  
Grins ◽  
Eklöf ◽  
Eriksson ◽  
Wardecki ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Prussian Blue ◽  
Co2 Adsorption ◽  
X Ray Diffraction ◽  
Alkali Cations ◽  
Prussian Blue Analogue ◽  
X Ray ◽  
Infra Red ◽  
Adsorption Desorption ◽  
Adsorption Capability

The CO2 adsorption on various Prussian blue analogue hexacyanoferrates was evaluated by thermogravimetric analysis. Compositions of prepared phases were verified by energy-dispersive X-ray spectroscopy, infra-red spectroscopy and powder X-ray diffraction. The influence of different alkali cations in the cubic Fm3m structures was investigated for nominal compositions A2/3Cu[Fe(CN)6]2/3 with A = vacant, Li, Na, K, Rb, Cs. The Rb and Cs compounds show the highest CO2 adsorption per unit cell, 3.3 molecules of CO2 at 20 C and 1 bar, while in terms of mmol/g the Na compound exhibits the highest adsorption capability, 3.8 mmol/g at 20 C and 1 bar. The fastest adsorption/desorption is exhibited by the A-cation free compound and the Li compound. The influence of the amount of Fe(CN)6 vacancies were assessed by determining the CO2 adsorption capabilities of Cu[Fe(CN)6]1/2 (Fm3m symmetry, nominally 50% vacancies), KCu[Fe(CN)6]3/4 (Fm3m symmetry, nominally 25% vacancies), and CsCu[Fe(CN)6] (I-4m2 symmetry, nominally 0% vacancies). Higher adsorption was, as expected, shown on compounds with higher vacancy concentrations.

scholarly journals COMPORTAMIENTO DE TORRE DE LAVADO A NIVEL DE ESCALA PARA LA REMOCIÓN DE H2S DE UN REACTOR ANAEROBICO DE FLUJO ASCENDENTE

2018 ◽  
Vol 27 (1) ◽  
pp. 85
Author(s):  
José A. Acaro R ◽  
Jeannie L. Quispe E. ◽  
Mali I. Salas D.
Keyword(s):  
Hydrogen Sulfide ◽  
Dissolved Oxygen ◽  
Coming Out ◽  
Packed Bed ◽  
Uasb Reactor ◽  
Sulfate Concentration ◽  
Hydrogen Sulfide Removal ◽  
Palabras Clave ◽  
Wet Scrubber ◽  
High Concentrations

Nuestro equipo en esta oportunidad hizo una simulación de una torre de lavado, la cual la aplicamos en el reactor UASB, a manera de escala construimos una torre de lavado compuesta por difusores, una cama de sólidos hecha de material de esponja, un tubo de acrílico y todas las conexiones que conducen el biogás con H2S. Los componentes a eliminar y/o remover fueron los gases que salen del reactor, en especial del H2S (gas odorífero y toxico que a grandes concentraciones pude llevar a la muerte y como resultado de sus reacciones con el ambiente puede causar daños en las estructuras con la cual este en contacto) mediante la oxidación con el oxígeno disuelto que proveen las microalgas presentes en el agua de la laguna terciara utilizada. Esta torre de lavado la montamos en las instalaciones de CITRAR‐UNI con el permiso del operador y vimos el comportamiento que tiene esta torre, mediante los monitoreos de oxígeno disuelto, temperatura, pH y sulfatos que realizamos durante tres semanas de monitoreo. Como resultados obtuvimos que la torre de lavado sí oxidaba y removía la contracción de H2S, ya que cuando pasaba el tiempo se consumía el oxígeno disuelto, además de esto también en el monitoreo de sulfatos pudimos observar un aumento de este parámetro es decir la torre si estaba consumiendo en H2S, y por esta razón también disminuyo el olor fétido que produce este gas. Palabras clave.- Torre de lavado, reactor UASB, remoción de sulfuro de hidrógeno. ABSTRACT The present work reports the simulation of a wet scrubber coupled to an UASB reactor. The scrubber consisted of baffles, packed bed of sponge material, an acrylic tube and all the connections necessary to bring the H2S‐ladden biogas. The purpose of the equipment is to eliminate some of the gases coming out of the reactor, through their oxidation by the dissolved oxygen provided by the microalgae present in the water from the tertiary lagoon. Hydrogen sulfide is a foul‐ smelling and toxic gas which can cause death at high concentrations, and can also cause damage to the structures with which it comes into contact. The scrubber was installed on the site of CITRAR‐UNI and the behavior of the equipment was monitored during three weeks by following the temperature, pH and the concentrations of sulfates and dissolved oxygen. The results have shown that the scrubber was effectively an oxidizing environment which was removing H2S, since the dissolved oxygen was actually consumed gradually. It was also observed that the sulfate concentration was increasing, indicating a consumption of H2S, which was also confirmed by a reduction in the odor of the gas. Keywords.- scrubber, UASB reactor, hydrogen sulfide removal .

scholarly journals CFD Simulation of CO2 and Methane Adsorption at Various Temperature for MOF-5 using Dual-site and Single-site Langmuir Model

CFD Letters ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1-10
Author(s):  
Mohd Zul Amzar Zulkifli ◽  
Azfarizal Mukhtar ◽  
Muhammad Faizulizwan Mohamad Fadli ◽  
Anis Muneerah Shaiful Bahari ◽  
Akihiko Matsumoto ◽  
...  
Keyword(s):  
Energy Demand ◽  
Carbon Capture ◽  
Cfd Simulation ◽  
Co2 Adsorption ◽  
Minimum Energy ◽  
Packed Bed ◽  
Methane Adsorption ◽  
Adsorption Model ◽  
Porous Media Model ◽  
Dual Site

The annual increase in energy demand has led to an increase in greenhouse gas emissions, in particular CO2 emissions from the power generation industry. Carbon Capture and Utilization are technologies applied to capture CO2 gases and transform the gases into a different energy source. The adsorption technology to capture CO2 gases was chosen due to the minimum energy consumption and low costs required for an industrial application for sustainability. Metal-Organic Framework (MOF) has a reasonably high CO2 adsorption capability. It has been applied as an adsorbent for capturing and storing CO2. In this study, a comparison of CFD simulation with experimental CO2 and methane adsorption values in solid adsorbent beds containing MOF-5 at various temperatures was presented. The simulation was performed using 2D and 3D models from 0℃ at STP to 130℃ for CO2 and methane gas molecules. In addition, the isothermal and kinetic adsorption model was added to the simulations. This includes Single- and Dual-Site Langmuir adsorption isotherm and Linear Driving Force. The porous media model was then activated to imitate packed bed adsorbent and measured the pressure drop from the simulation. The results showed that the CO2 adsorption values of MOF-5 decrease as the adsorbent temperature increases. There was a decline of 0.002 mmol/g of adsorbed CO2 molecules per 10-kelvin difference. The CO2 adsorption value was 0.53 mmol/g at STP and 1.15 mmol/g for CH4 at STP. Both CO2 and CH4 adsorption were used to suggest optimal CO2 adsorption for the Pressure Swing Adsorption cycle.

scholarly journals Fungal cellulases: production by solid-state cultivation in packed-bed bioreactor using solid agro-industrial by-products as substrates and application for hydrolysis of sugarcane bagasse

2020 ◽  
pp. 2097-2116 ◽  
Author(s):  
Priscila Aparecida Casciatori Frassatto ◽  
Fernanda Perpétua Casciatori ◽  
João Cláudio Thoméo ◽  
Eleni Gomes ◽  
Maurício Boscolo ◽  
...  
Keyword(s):  
Solid State ◽  
Sugarcane Bagasse ◽  
Enzyme Production ◽  
Packed Bed ◽  
Aeration Rate ◽  
Hydrolysis Time ◽  
Enzymatic Extract ◽  
Packed Bed Bioreactor ◽  
High Concentrations ◽  
Hydrolysis Of

Cellulases are essential for the hydrolysis of lignocellulosic materials in the production of second generation ethanol. Solid-state cultivation is a process that provides high concentrations of enzymes that can be used in this hydrolysis. The objectives of this work were to produce cellulases by cultivating the fungus Myceliophthora thermophila I-1D3b in a packed bed bioreactor with sugarcane bagasse (SCB) and wheat bran (WB) as substrate and to evaluate the efficiency of the enzymatic extract in the hydrolysis of SCB in natura (BIN) and pretreated with ozone, alkali and ultrasound (BOU). The conditions for enzyme production in the bioreactor were SCB:WB at a ratio of 2.3:1 (w/w), 75 % moisture content; 45 ºC; aeration rate 240 L h-1 and 96 h. The enzyme production was evaluated by endoglucanase, xylanase, filter paper (FPU) and ?-glycosidase activities. For the application of the enzymes, a central composed response surface design with 5 repetitions of the central point was used, taking enzyme volume and hydrolysis time as factors. Such cultivation yielded the following enzymatic activities: 723 U gss-1 of endoglucanases, 2024 U gss-1 of xylanase, 12.6 U gss-1 of FPU and 41 U gss-1 of ?-glucosidase. The results of the application tests indicated the best conditions as 7.0 ml of the enzyme extract (4.2 FPU) and 6 hours for BIN and BOU. The best cellulose-glucose conversions were obtained for BOU, reaching 32.1 % at 65 ºC. In conclusion, the enzyme production in the packed bed bioreactor was efficient and BOU pretreatment improved the hydrolysis of biomass, increasing the efficiency of conversion of cellulose to glucose.

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